Molecular Mechanisms of Sex Determination and Differentiation

这项国际合作研究是将多种方法和动物系统结合起来研究性别决定和性别分化。地方性海豚的性别变化为研究性别决定和性别分化的机制提供了一个理想的模型系统。我们首次用免疫细胞化学方法检测了性转变过程中不同阶段鲤鱼中P450胆固醇侧链裂解酶(P450scc)的性腺部位。P450scc细胞主要分布在正常女性的膜层。随着女性性别的改变，P450scc的定位从膜层向间质转移。在变性过程中，P450scc细胞数量似乎有所增加。然而，性腺产生雌激素的能力在性别变化的最早阶段就永久性地丧失了。在睾丸…中检测不到芳香酶基因和蛋白质的水平，芳香酶负责将雄激素转化为雌激素。更多和过渡性性腺。在这项合作研究中，我们还使用四种类固醇代谢酶(P450scc，3beta-HSD，P450c17，P450arom)的多克隆抗体，用免疫细胞化学方法检测了罗非鱼性腺分化过程中类固醇产生细胞的初始分化和发育。P450scc、3beta-HSD、P450c17和P450arom的免疫反应首次在形态性别分化前几天检查的遗传雌性性腺中出现。相反，在性别分化过程中，所有四种类固醇生成酶的阳性免疫染色在睾丸中都很难识别。孵化30天后，P450scc、3beta-HSD和P450c17在睾丸传出管周围的组织中有微弱的表达，而P450arom则不表达。在精子发生开始之前，睾丸中免疫反应细胞的数量以及染色强度增加。综上所述，这些发现表明雌激素在鱼类卵巢分化中起着重要作用。这项合作研究的结果还表明，雌激素在爬行动物依赖温度的性别分化中起着重要作用。较少

This international collaborative research is to combine a variety of approaches and animal systems to the study of sex determination and sexual differentiation. Sex change in the endemic, Hawaiian wrasse Thalassoma duperrey provides an ideal model system to investigate mechanisms of sex determination and sexual differentiation. We first used immunocytochemical methods to detect gonadal sites of P450 cholesterol side-chain cleavage enzyme (P450scc) in the wrasse at different stages of in the sex change process. P450scc cells were predominantly in the theca layr of normal females. As females underwent sex change, P450scc localization shifted from the theca layr to the interstitium. P450scc cells appeared to increase in number midway through sex change. The gonad's ability to produce estrogens, however, is permanently lost in the earliest stages of sex change. The levels of aromatase mRNA and protein, the enzyme responsible for converting androgens to estrogens, was undetectable in testes … More and transitional gonads. In contrast, protein levels of 11beta-hydroxylase, the enzyme responsible for 11-ketotestosterone production increase towards the end of sex change process.In this collaborative research, we also examined immunocytochemically the initial differentiation and development of steroid-producing cells during gonadal sex differentiation in tilapia Oreochromis niloticus using polyclonal antibodies against four steroid-metabolizing enzymes (P450scc, 3beta-HSD,P450c17, P450arom). Immunoreaction for P450scc, 3beta-HSD,P450c17, and P450arom became evident for the first time in gonads of genetically females examined at several days before morphological sex differentiation. In contrast, positive immunostaining for all four steroidogenic enzymes was not easily identified in the testes during sex differentiation. A weak staining for P450scc, 3beta-HSD and P450c17, but not P450arom, was present in the tissue surrounding the efferent duct in testes 30 days after hatching. The number of immunoreactive cells as well as the intensity of staining ware increased in testes just before the onset of spermatogenesis. Taken together, these findings suggest that estrogens play an important role in ovarian differentiation in fish. The results of this collaborative research also suggest an important role of estrogens in temperature-dependent sexual differentiation in reptiles. Less